Robotic vacuum cleaners such as for example robotic vacuum cleaners are known in the art. In general robotic vacuum cleaners are equipped with drive arrangement in the form of a motor for moving the cleaner across a surface to be cleaned. The robotic vacuum cleaners are further equipped with intelligence in the form of microprocessor(s) and navigation means for causing an autonomous behaviour such that the robotic vacuum cleaners freely can move around and clean a space in the form of e.g. a room.
In many fields of technology, it is desirable to use robots with an autonomous behaviour such that they freely can move around a space without colliding with possible obstacles.
It is a desire to support the navigation and positioning of a robotic vacuum cleaner, especially within complex environments and surfaces to be cleaned. The navigation and positioning may thus be improved by using artificial markers or artificial landmarks.
As an a example, robotic vacuum cleaners exist in the art with the capability of more or less autonomously vacuum cleaning a room in which furniture such as tables and chairs and other obstacles such as walls and stairs are located. Traditionally, these robotic vacuum cleaners have navigated a room by means of using e.g. ultrasound or light waves or laser beams. Further, the robotic vacuum cleaners typically must be complemented with additional sensors, such as stair sensors, wall-tracking sensors and various transponders to perform accurately. Such sensors are expensive and affect the reliability of the robot.
A large number of prior art robotic vacuum cleaner use a technology referred to as Simultaneous Localization and Mapping (SLAM). SLAM is concerned with the problem of building a map of an unknown environment by a mobile robotic vacuum cleaner while at the same time navigating the environment using the map. This is typically combined with a horizontally scanning laser for range measurement. Further, odometry is used to provide an approximate position of the robot as measured by the movement of the wheels of the robot.
US 2002/0091466 discloses a mobile robot with a first camera directed toward the ceiling of a room for recognizing a base mark on the ceiling and a line laser for emitting a linear light beam toward an obstacle, a second camera for recognizing a reflective linear light beam from the obstacle. The line laser emits a beam in the form of straight line extending horizontally in front of the mobile robot.
The use of a base mark on the ceiling and markers on the ceiling in general poses certain disadvantages. First, the robot will need to have two cameras with at least one camera “looking” up towards the ceiling and another camera looking in the direction of movement and thus in the direction of the laser beams from the horizontal line laser, this is expensive and complicates the build up of the robot. Further, the user has to position at least one base mark on the ceiling by using a chair or ladder.
In addition if the robotic vacuum cleaner can only rely on natural landmarks or markers within a surface to be cleaned, or if the environment is too sterile, too repetitive, thus if the signature of the environment is not rich enough, the robotic cleaning device may run into problems during the navigation and when it tries to identify its current position.
It is further difficult to communicate special information to the robotic cleaning device.